Automobile disc brakes function by attaching a rotor to a spindle about which a wheel rotates. A brake pad is provided which is made to contact the rotor by the action of a caliper. When the caliper is activated, the brake pad rubs against the rotor and frictional contact of the brake pad and the rotor causes the rotor to slow down and stop turning.
A typical brake pad comprises a brake shoe, consisting of a metal (e.g., steel) plate which mounts into the caliper, and a friction member or brake lining affixed to the brake shoe. The brake lining is that part of the brake pad that actually comes into contact with the rotor when the caliper is activated. The brake lining is composed of a friction material, of which asbestos has traditionally been a major component.
It would be highly beneficial to provide a composite friction assembly comprising a lightweight, reinforced plastic support member capable of withstanding the rigorous conditions typically encountered in automobile disc brakes. Such a brake pad will be of substantially lighter weight than current brake pads which comprise metal support members. A reduction in the weight of automobile components is extremely desirable since it results in improved fuel efficiency which has been a government-mandated objective for automobile manufacturers.
Preferably, the composite friction assembly should be simple and inexpensive to manufacture. Accordingly, the composite friction assembly should allow for the use of a friction member composed of conventional friction materials and conventional friction resins, as well as organic, non-asbestos organic, semi-metallic, or low-metallic materials. In addition, the boundary layer between the friction member and the support member should be substantially planar and of minimal thickness.
The problems associated with known composite friction assemblies are solved to a large degree in accordance with the present invention.